because Kostya Tszyu has that "russian/euro" style of fighting, he tends to have trouble fighting on the inside:
his style now looks different from when he started in the amatuers, and even when he was a younger Pro.
Maybe it is age...he doesn't move his head at all like he used to, nor does he have that aggression...he also tends to get caught up in his hype and starts to revert back to the Vince Philip-Tszyu, where he thinks he can stand toe to toe and knock you out with his power; he also becomes to relaxed after a big win and loses that hunger.
For his style:
he doesn't keep his punches close to his body, which is one of his problems when fighting on the inside...look at Duran, Tyson, and yes, Hatton, all keep their punches close/tight, to make the punches shorter, more compact with power, and have the ability to throw quick combinations.
He also doesn't stick his jab, he just likes to use it to measure {which isn't really part of that style because Wlad loves to stick the jab into his opponents face}.
He rarely throws the uppercut, which would of been another good weapon against Hatton.
He doesn't side step like he should, nor does he use the defensive gaurd right.
I highly doubt it would of been hard for someone like Tszyu to alter his style a bit...like, Stick the jab, used as a weapon, not a measuring stick...or throw short, compact, punches...move his head...keep his guard up when being attacked, etc.
TSZYU NEEDED AN AMERICAN TRAINER
No matter what, Hatton used the "Grapple" way of fighting to wear down the older, much more inactive fighter because he knew this was the way to win...if he thought he could out-box Tszyu, he would of, but obviously he was right on his understanding he couldn't without wearing him out first...why? because he was starting to get out-boxed by a 35 year old, inactive, injury prone, now tired from 6 rounds of grappling, fighter...if it wasn't for the fatigue, Tszyu would of won in my opinion. I was acutally surprised that Hatton was having trouble with the fatigued Tszyu.